I have nothing to add to @paulakreuzer’s explanation of what TWRP is (not a virus).
The recovery can be deleted, but this is rarely done deliberately, as the recovery program on a smartphone does nothing if it is not running, and it only runs when the phone boots into it, it doesn’t run in the background of the OS or anything.
It’s mainly there to provide ways to recover (hence the name) the phone from a state in which something’s wrong with the OS or with the interaction of OS, Apps and data. Some maintenance options apart from that might be added.
Whether a Fairphone Angel can delete the recovery would depend on the Angel’s experience with the phone. Fairphone Angels are volunteers helping others in their spare time, their expertise may vary.
Normally, I think they would be glad to find TWRP still working on a Fairphone 2 with possible OS trouble.
Not directly, but …
… and TWRP was part of this upgrade, but that’s not really important. Important is: There’s a recovery program on the phone. At least with Android that’s standard procedure.
Before TWRP Fairphone OS just came with a different recovery program (the stock recovery program Google provides for Android). Without the upgrade, you just would have seen a different screen … the Android robot lying on its back, maintenance flap on its belly opened, perhaps with a red warning sign in front.
If you are curious, somebody took the time to write a detailed guide with screenshots here … it’s for a different device and an older TWRP 3.x version, but in general TWRP works the same on many devices, and the basic set of options is the same at least in the current 3.x versions, so …
No idea? …
I want to be constructive here.
A smartphone is a full-blown computer in miniature form and with the ability to phone. The manufacturers of smartphones all do their best to hide this simple and potentially sales hindering fact behind a simplified, ideally more easy to use front, but the engine room in the background looks and works at least as quirky as any quirky desktop computer or notebook.
Full-blown computers need some knowledge and care (or a person around who can provide those, just ask my family 
), and because of this they are not everybody’s favourite thing to use, that’s one of the reasons why in the realm of phones “dumber” devices are still available, with new ones introduced every year, because they still sell.
What are you really doing with your smartphone which your old Samsung phone can’t do? Or what would you potentially want to do?
Depending on that, there might be options for you where less can go wrong.